1. Field of the Invention
This invention relates to a detergent composition capable of minimizing yellowing of clothes.
2. Description of the Prior Art
When worn, clothes become contaminated with soils and stains such as sebum soils secreted from bodies, particles of dirt or dust, oil stains and the like. Detergents have been employed to remove physicochemically these soils or stains adhering on clothes, to restore the cleanliness of the clothes. However, as is well known in the art, none of the conventional detergents can remove such soils and stains completely and portions of the soils and stains remain in clothes after washing.
Various attempts have been made to obtain more complete removal of soils and stains. For instance, the physicochemical activities of detergents represented by surface active agents were at first utilized, and the biochemical activities of enzymes and the chemical activities of detergents represented by bleaching agents have been utilized. However, in spite of these efforts, complete removal of soils and stains has not yet been attained. Thus, small quantities of soils and stains are left on clothes and, as is well-known, these soils and stains accumulate by repetition of wearing and washing.
In view of the foregoing, it may be considered that in the detergent art it is desired to solve the important problem of attaining a complete removal of soils and stains. However, there is another important problem to be solved, i.e, the problem of preventing yellowing of fibrous clothes. The yellowing phenomenon is caused mainly by autoxidation of soils and stains left unremoved by washing, especially residual sebum soils.
A significant portion of the soil or dirt that adheres on clothes is sebum soil, about 50 percent by weight of which is unsaturated hydrocarbons and unsaturated aliphatic derivatives represented by squalene, triolein and oleic acid. It is confirmed that significant amounts of such unsaturated compounds are present in the soil or dirt that remains on clothes after washing. These unsaturated compounds undergo autoxidation and cause rancidity and give an offensive smell on wearing. Further, they cause yellowing even after washing. It is also known that yellowing by dye-stuffs and self-yellowing of fibers are due to autoxidation.
Various attempts have been made to provide detergent compositions capable of preventing or masking yellowing. For instance, redeposition preventing agents such as carboxymethyl cellulose and various fluorescent whitening agents are incorporated in detergents. However, the problem has not completely been solved as yet.
It is therefore a primary object of this invention to provide a detergent composition which can prevent or at least substantially reduce coloration and yellowing in clothes and generation of offensive smells.